Device for examining filled containers by means of X-Rays and use of this device

ABSTRACT

The invention related to a device for examining filled containers for foreign bodies. In an embodiment, the device for examining filled containers for foreign bodies has a transport apparatus for transporting the containers individually in succession in a row on a plane of transport, at least one X-ray source which emits X-rays in a predetermined direction, and an apparatus for recording the X-rays after they have passed through the containers. In an embodiment, the direction in which the X-rays are emitted from the X-ray source is inclined by between 10° and 60° to the plane of transport. In an embodiment, two X-ray sources are provided, namely one arranged above and one below the plane of transport. In an embodiment, the X-ray source is positioned such that the ray course is approximately tangential to the maximum slope of the bulge of the container bottom.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application claims priority from patent applicationPCT/EP2003/012632 filed Nov. 12, 2003, which claims priority from GermanPatent Application Number 202 17 559.6, which was filed on Nov. 12,2002, the entire content of which is herein incorporated by reference.

FIELD OF THE INVENTION

This invention relates to packaging. More particularly, it relates toexamining containers for foreign bodies.

BACKGROUND OF THE INVENTION

The examination of goods which are packed in containers, for example,fruit juices in drink bottles, by means of X-rays is a process known inthe food industry. Problems arise when checking for foreign bodies thathave a higher density than the packed goods and, therefore, fall to thebottom of the containers. In the case of containers with a dishedbottom, as is the case with many drink bottles, the foreign bodies slideon the bulge of the container bottom to the inner container edge. There,they are hard to recognize by means of X-rays, as the X-rays mustpenetrate not only the vertical container wall but also the bottom ofthe container. During this process the bottles are oriented, because ofthe bulge of the container bottom, at an angle of, for example, 10° tothe dished surface of the container bottom and therefore travel a verylong distance inside the container material. An additional attenuationof the X-rays by any foreign bodies present therefore has onlyrelatively little effect and is frequently no longer detectable. Also,unevennesses in the surface of the container bottom can easily bemistaken for a foreign body.

EP-A-0 795 746 discloses examining the containers using two X-rays, oneof which points 45° in the direction of transport and the other of whichpoints 45° against the direction of transport, with the result that theyare at right angles to each other.

EP-A-0 961 114 discloses turning the containers upside down for thisexamination so that any foreign bodies present drop down to the top ofthe container near the closure where they can be recognized withcertainty by means of X-rays.

WO 01/44791 discloses tilting the containers sideways by roughly 80° andthen examining them for foreign bodies using a vertically directedX-ray.

BRIEF SUMMARY OF THE INVENTION

The invention is directed to a device for examining containers forforeign bodies. In an embodiment, the device comprises a transportapparatus for transporting the containers individually, in succession,in a row on a plane of transport. An X-ray source for emitting an X-rayin a predetermined direction and an apparatus for recording the X-raysafter they have passed through the containers are also included.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an embodiment of a device according to theinvention wherein the X-ray is directed downward at the container at anangle of 30° towards the plane of transport;

FIG. 2 is a front view of an embodiment of a device according to theinvention wherein the X-ray is directed upward at the container at anangle of 30° towards the plane of transport;

FIG. 3 is a front view of an embodiment of a device according to theinvention with two X-rays directed at the container; and

FIG. 4 is a side view of the device of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-4, the invention is directed to an apparatus for thedetection of foreign bodies in filled containers. The apparatus will nowbe described in detail with reference to the figures.

In an embodiment, as shown in FIGS. 1-4, the containers are drinkbottles 10 which, in the lower area, have a cylindrical wall 12 and adished bottle bottom 14. In an embodiment, the bottles 10 areconstructed of glass. The bottles 10 are transported standing upright ona transport apparatus 16. The top of the transport apparatus 16 definesa plane of transport. The transport apparatus 16 can be a customarylink-chain conveyor with plastic chain links. If the chain linksinterfere on the X-ray image, a belt conveyor can be used in which thecontainers 10 are transported by means of two laterally engaging belts.In belt conveyor transport apparatuses, as disclosed in EP-A-0 124 164,the bottom 14 of the containers 10 is not supported. In a belt conveyortransport apparatus, the plane of transport is defined by the containerbottoms 10. It preferably lies horizontal. However, it can also beinclined, particularly when using a belt conveyor.

An X-ray source 18 is arranged at a distance next to one side of thetransport apparatus 16. The X-ray source 18 may produce x-rays 24 of anysuitable energy level. Suitable X-ray sources 18 may produce, forexample, an X-ray 24 with 50 to 100 keV. In an embodiment, a 60 keVX-ray source 18 is used. Dished container bottoms 14 generally have amaximum slope of between approximately 10° and 60° at the edge.Therefore, in an embodiment, the X-ray source 18 is positioned suchthat, at the point of the maximum slope of the container bottom 14—whichis generally at the edge of the container bottom 14—the course of theX-ray 24 is roughly tangential to the bulge of the container bottom 14,as shown in FIGS. 1-3. This can be achieved by having an X-ray source 18arranged either above the plane of transport or below the plane oftransport. In either case, the X-rays 24 are preferably aligned roughlyat a right angle to the direction of transport.

An apparatus for recording the X-rays 24 is on the other side of thetransport apparatus 16. The apparatus for recording the X-rays 24 isarranged on the side of the transport apparatus 16 lying opposite theX-ray source 18. This apparatus can be a line of X-ray detectors or atwo-dimensional field of X-ray detectors. In an embodiment, the X-raydetectors are photodiodes with a scintillation crystal. In anotherembodiment, the recording apparatus is an area sensor, for example, anX-ray image converter 20 or an X-ray image intensifier, with adownstream photographing device such as a CCD camera 22. Through the useof such an area sensor, the necessary exposure time is minimized and theexposure of the product and the environment to the ray is thus reduced.

If the X-ray source 18 is arranged above the plane of transport, theupper part of the X-ray 24 travels, in the area of the inner edge of thecontainer bottom 14 facing away from the X-ray source 18, approximatelytangentially to the bulge of the container bottom 14. As a result, theX-ray 24 penetrates the material of the container 10 only on the frontand on the back of the wall 12, but does not travel an extended distanceinside the container bottom 14. If the inclination is, for example, 30°,the section inside the vertical container wall 12 increases by onlyapproximately 15%. Consequently, the contrast of intensity differencesthat is caused by foreign bodies is reduced only to an insignificantextent.

Similarly favorable conditions apply in the area of the inner edge ofthe container bottom 14 facing the X-ray source 18. Here the containerbottom 14 rises at an angle of, for example, 30°, and so the X-ray 24then travels at an angle of 60° to the container bottom, with the resultbeing that here too the distance travelled is extended by onlyapproximately 15% compared with an incidence at a right angle.

In the embodiment shown in FIG. 1, the X-ray 24 is inclined by an angleof 30° down towards the plane of transport. The distance between theX-ray source 18 and the transport apparatus 16 is approximately 30 cmand the X-ray 24 has a divergence of 15°, with the result that the wholebottle bottom 14, which has a diameter of approximately 7 cm, lieswithin the X-ray 24. The X-ray image converter 20 is arranged at thesmallest possible distance next to the transport apparatus 16 and coversat least the area of the X-ray 24 which has penetrated the bottle bottom14.

In the embodiment shown in FIG. 1, there is a foreign body 26, forexample, a glass splinter, on the side facing away from the X-ray source18 of the inner edge of the bottle bottom 14. The foreign body 26absorbs or scatters the X-rays 24 and can be recognized on the X-rayimage converter 20 as a dark spot 32. As can be seen in FIG. 1, the raysin the immediate vicinity of the rays which strike the foreign body 26penetrate the front and back of the wall 12 of the bottle 10 at an angleof approximately 60°. This also applies to the rays travellingimmediately thereunder, which travel approximately tangentially to thebulge of the edge of the bottle bottom 14. On the other hand, the rayslying somewhat deeper travel a relatively long distance inside thebottle bottom 14 and are thereby very markedly attenuated. Unevennessesin the top or bottom of the bottle bottom 14 has a particularly markedeffect on the deeper rays. The rays in the immediate surroundings of theforeign body 26 are very uniformly attenuated, however, with the resultbeing that the foreign body 26 can be recognized through a clearbrightness contrast on the X-ray image converter 20.

The X-ray 24 can also be directed from below at an angle of, forexample, 30° to the plane of transport towards the container bottom 14.In the area of the edge of the container bottom 14 facing the X-raysource 18, the X-ray 24 then travels approximately tangentially to thebulge of the container bottom 14, whereas in the area of the inner edgeof the container bottom 14 facing away from the X-ray source 18, it thentravels, in the chosen case, at an angle of approximately 60° to thecontainer bottom 14.

In the embodiment shown in FIG. 2, the X-ray source 18 is arranged belowthe plane of transport, and the X-ray 24 is directed at an angle of 30°upward towards the plane of transport. The same foreign body 26 as inFIG. 1 also stands out clearly against its surroundings in this case.The resulting angle at which the rays in the area surrounding the raystriking the foreign body 26 are directed towards the bottle bottom 14is 30° plus the slope of the edge of the bottle bottom 14, which istypically also 30°. Any unevennesses in the material thickness in thebottle 10 thus has only a slight effect. As regards the arrangement ofthe X-ray image converter 20 and the CCD camera 22, the embodiment ofFIG. 2 corresponds to that of FIG. 1.

The conditions as regards the course of the X-rays 24 to the bulge ofthe bottle bottom 14 and to the container walls 12 are transposed in theembodiments of FIGS. 1 and 2 if the foreign body 26 is located on theside of the bottle bottom 14 facing toward the X-ray sources 18 insteadof on the side facing away from the X-ray sources 18 of the bottlebottom 14.

In an embodiment of the invention, the containers are examined using twoX-rays 24. In this embodiment, one of the X-rays 24 is directed towardsthe container bottom from above, and the other X-ray 24 is directedtowards the container bottom from below. Both X-ray sources 18 arepreferably arranged on the same side of the transport apparatus 16. Theangles at which the X-rays 24 are directed towards the container bottom14 can be the same or different. They are preferably approximately 30°.It is also possible to use still further X-ray sources 18, for example athird X-ray source 18 which directs an X-ray parallel to the plane oftransport or at a different angle from the first and second X-raysources 18 onto the container bottom 14. The angle of the X-rays 24 tothe direction of transport can also be different.

FIGS. 3 and 4 illustrate an embodiment in which two X-ray sources 18 areprovided. As shown in FIGS. 3-4, the X-ray 24 emitted from the firstX-ray source 18 arranged above the plane of transport is directeddownward towards the plane of transport at an angle of 30°. The secondX-ray source 18 is arranged below the plane of transport, and the X-ray24 emitted from it is directed upward towards the plane of transport atan angle of 30°.

When using two X-rays 24, the images are preferably coupled on an areasensor. The divergence angle of the X-rays 24 and the distance betweenthe X-ray sources and the transport apparatus 16 on one side and thedistance between the area sensor and the transport apparatus 16 on theother side are matched to each other such that the image produced by theX-ray 24 coming from below appears in the upper half of the area sensor,while the image produced by the X-ray 24 coming from above appears inthe lower half of the area sensor. Defects which emerge in one image canbe sought and confirmed in the other image. As shown in FIGS. 3-4, thedistance between the X-ray sources 18 and the transport apparatus 16,the divergence of the emitted X-rays 24, and the size of the X-ray imageconverter 20 and its distance from the transport apparatus 16 are chosensuch that the first image 28 produced by the first X-ray 24 is locatedin the lower half of the X-ray image converter 20 and the second image30 produced by the second X-ray 24 is located in the upper half of theX-ray image converter 20. In FIGS. 3-4, the foreign body 26 is againarranged as in FIGS. 1 and 2, and it produces a spot 32 of reducedbrightness both in the first image 28 and in the second image 30. In anembodiment, both images are taken using a single CCD camera 22.

An apparatus for recording the X-rays 24 and for evaluating theinformation is allocated to each X-ray source 18. By comparing theinformation supplied by the individual recording apparatuses, athree-dimensional position determination of the defects is possible, asa result of which foreign bodies can be distinguished from defects inthe material of the container wall 12. The precise spatial position ofthe foreign body 26 can be established from the position of the twospots 32 using customary image-processing methods. If this position lieson the outside of the wall 12 of the bottle 10, it can be concluded fromthis that it is not a foreign body 26 inside the bottle 10 but may be,for example, a raised point on the outside of the wall 12. The bottle 10is then not defective.

As regards the accuracy of recognition and the sharpness of contrast ofthe spot 32 of reduced intensity caused by the foreign body 26 on theX-ray image converter 20, the same conditions are obtained in theembodiment of FIG. 1 as for the first image 28 of FIG. 3, and the sameconditions are obtained as in the embodiment of FIG. 2 in the case ofthe second image 30. The conditions are again transposed if the foreignbody 26 is located on the side of the bottle bottom 14 facing the X-raysources 18.

The subject-matter of the invention is also the use of the previouslydescribed device for examining filled containers 10 for foreign bodies26, in particular glass bottles 10 with a dished bottom. The X-raysource 18 or the X-ray sources 18 are preferably positioned such that,at the point of the maximum slope of the container bottom 14, the courseof the ray is roughly tangential to the bulge of the container bottom14.

1. A device for examining filled containers for foreign bodies, thedevice comprising: a transport apparatus for transporting the containersindividually in succession in a row on a plane of transport wherein theplane of transport is substantially horizontal and is defined by a topof the transport apparatus; at least one X-ray source for emitting anX-ray in a predetermined direction, wherein the predetermined directionis inclined by between approximately 10° and approximately 60° to theplane of transport; and at least one apparatus for recording the X-raysafter they have passed through the containers.
 2. The device of claim 1,wherein: a first X-ray source and a second X-ray source are provided;the first X-ray source is arranged above the plane of transport and itsX-rays are directed downward towards the plane of transport; and thesecond X-ray source is arranged below the plane of transport and itsX-rays are directed upward towards the plane of transport.
 3. The deviceof claim 2, wherein: the at least one apparatus recording the X-raysafter their passage through the containers is a member of a plurality ofapparatuses for recording the X-rays; one of the plurality ofapparatuses is allocated to each X-ray source; and the X-rays recordedby the recording apparatuses are compared with one another in anevaluation apparatus.
 4. The device of claim 2, wherein the rays of thefirst and second X-ray sources fall onto, respectively, first and secondareas of the apparatus for recording the X-rays.
 5. The device of claim1, wherein the apparatus for recording the X-rays is an X-ray imageconverter with a downstream digital camera.
 6. (canceled)
 7. (canceled)8. The device of claim 1, wherein the at least one X-ray source ispositioned such that a ray course is approximately tangential to amaximum slope of a bulge of a bottom of the container.
 9. A method ofexamining filled containers for foreign bodies, the method comprising:transporting at least one filled container on a substantially horizontalplane of transport; passing the container through X-rays having apredetermined direction; and recording the X-rays after they passthrough the container.
 10. The method of claim 9, wherein the at leastone filled container is one of a plurality of filled containers beingtransported individually in succession in a row on the plane oftransport.
 11. The method of claim 9, wherein the predetermineddirection of the X-rays is inclined by an angle to the plane oftransport, the angle measuring approximately between 10° to 60°.
 12. Themethod of claim 9, wherein: the X-rays are generated by at least oneX-ray source; and the at least one X-ray source is positioned such thata ray course is approximately tangential to a maximum slope of a bulgeof a bottom of the container.
 13. The method of claim 9, wherein theX-rays are generated by a first X-ray source positioned above the planeof transport and a second X-ray source positioned below the plane oftransport.
 14. The method of claim 9, wherein the step of recording theX-rays after they pass through the container is performed by an X-rayimage converter and a digital camera.